Fig. 1.

Pathogenesis of post-Covid-19 pulmonary fibrosis: Covid-19 leads to pulmonary fibrosis through iatrogenic pathway, therapy with high oxygen concentration or mechanical ventilation cause oxygen toxicity, which induces the production of reactive oxygen species (ROS) and connective tissue growth factors (CTGFs). The pathological pathway through SARS-CoV-2 induces downregulation of angiotensin-converting enzyme 2 (ACE2) with subsequent activation of AngII, p38 mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3). Together, AngII, MAPK and STAT3 activate the production of transforming growth factor beta1 (TGFβ1). Both AngII and TGFβ1 activate fibroblast activation with subsequent development of pulmonary fibrosis